My Sony Xperia Tablet Z LTE has been running with Android KitKat 4.4.4 for quite a while now. An issue, where I couldn't save movies on the external SD card anymore, was fixed by rooting the device and then install an SD Card Fix (see Sony Xperia Tablet Z with Kitkat: Fix for permission denied on sd card).
For a couple of weeks now I got the notification, that a new software update is available, which would install Android Lollipop (5.0) on the device.
I decided to go for it and install the update using the over the air update (OTA). Download was working fine but whenever the tablet tried to install the new Android version, it rebooted and back in Kitkat showed an error:
Could not install new software version. Try again.
I did try again. Several times. Same problem.
Eventually I came across a good hint in the Sony Mobile forums, where "PCC" was mentioned. PCC is short for Sony PC Companion, a software installed on your computer to manage your Sony device (similar to Samsung's Kies).
Finally with PCC I was able to install the software update on the device, without any issues.
My Sony tablet is now running with the following versions:
- Model number: SGP321
- Android version: 5.0.2
- Kernel version: 3.4.9-perf-g8fa3dae
- Build number: 10.6.A.0.454